1. Field
The disclosure relates to thermal management for power management integrated circuits (PMIC's).
2. Background
Power management integrated circuits (PMIC's) are circuits specifically designed to manage the power consumption of a system. In particular, a PMIC may process the raw voltage from a power supply, such as a battery, and in turn supply regulated voltages to drive a plurality of off-chip power consumption entities separate from the PMIC. Modern PMIC's are becoming increasingly integrated due to greater system complexity. A typical PMIC may include many high-power on-chip modules for driving off-chip power consumption entities, such as switched-mode battery chargers (SMBC's), back light display drivers (WLED's), buck regulators, audio amplifiers, and flash LED drivers. The on-chip modules may dissipate considerable power when processing power to or from the off-chip entities.
In some system implementations, concurrent use scenarios for the power consumption entities may rapidly drive up the power dissipation of the PMIC, and in turn cause the temperature of the chip to exceed the thermal limits (e.g., 150° C.) of the silicon and the package. For example, in a typical PMIC, maximum power dissipation can be up to 8 Watts if all power consumption entities operate concurrently. On the other hand, to keep the junction (or die) temperature below 125° C., the maximum allowable power dissipation on the die may be closer to 2 Watts, assuming a typical package theta-JA and up to 85° C. ambient temperature.
To manage the PMIC power dissipation and ensure that the junction temperature does not exceed maximum limits, prior art techniques may call for monitoring and software control of the PMIC by a separate entity, e.g., a separate microprocessor coupled to the PMIC through the external pins of the PMIC. It will be appreciated that this approach to thermal management of the PMIC may cause significant latency, as a microprocessor would need to communicate with the PMIC over an interface, and such latency could undesirably result in thermal shutdown of the PMIC for certain concurrent use cases. Alternatively, prior art techniques may include performing coarse temperature monitoring and module control on the PMIC itself. However, such coarse techniques may not provide the flexibility and control of more sophisticated algorithms that may be implemented using a separate microprocessor.
In light of these considerations, it would be desirable to provide improved techniques for thermal management of a PMIC.